The present invention relates to functionalized, structurally modified silicas, a process for their preparation and their use.
It is known to react silicon dioxide obtained by flame hydrolysis and with a surface area of 40 to 200 m2/g with 3-methacryloxypropyl-trimethoxysilane. The resulting silicon dioxide is then coated with a further shell of (meth)acrylate polymers and subsequently employed in dental compositions (EP 0 142 784 A1).
It is known to silanize a silica with hexamethyldisilazane and then to destructure or to compact it by mechanical effects (EP 0 808 880 A2).
The known silica has the disadvantage that it can be incorporated into coating systems only with difficulty or not at all because its thickening effect is too high.
It is therefore an object of the present invention to develope a functionalized, structurally modified silica which does not have this disadvantage.